When i shower my feet turn really red they also turn red when i stand for a long time & when i just sit in school why is this ?

You may have some: degree of neuropathy or hypersensitivity to local swelling from dependence position... The simplest explanation is blood pooling in the extremities, which could be a symptom of several conditions including poor circulation, to deep vein thrombosis, to obesity, to venous stasis disorder. If this continues, you need to see a healthcare provider for proper diagnosis and treatment plan.